Acute Limb Ischaemia

Acute limb ischemia occurs due to a sudden decrease in the blood flow to a limb, resulting in a potential threat to the viability of the extremity. Unfortunately, the threat is not only to the limb, but these patients are also at high risk for death. Limb hypoperfusion results in systemic acid-base and electrolyte abnormalities that impair cardiopulmonary and renal function. Successful reperfusion may result in the release of highly toxic free radicals, further compromising these critically ill patients.

Therapeutic choices are often few and patient expectations are not always realistic. The management of acute limb ischemia requires a thorough understanding of the anatomy of the arterial occlusion and the open surgical and percutaneous options for restoring limb perfusion. Priorities for the diagnosis and effective management of these critically ill patients are provided.

According to the 2007 Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II), acute limb ischemia is defined as a sudden decrease in limb perfusion that causes a potential threat to limb viability (manifested by ischemic rest pain, ischemic ulcers, and/or gangrene) . Patients who present later than two weeks after the onset of the acute event are considered to have chronic limb ischemia.

The management of acute arterial occlusion remains a challenge for vascular specialists. Surgical thromboembolectomy and bypass grafting were the mainstays of therapy for many years . Subsequently, thrombolytic therapy and percutaneous transluminal angioplasty (PTA) have become treatment options for selected patients .

Despite these advances, the morbidity, mortality, and limb loss rates from acute lower extremity ischemia remain high . Thus, regardless of the treatment modality used, early diagnosis and rapid initiation of therapy are essential in order to salvage the ischemic extremity. The major causes of and management approaches to acute limb ischemia will be reviewed here. Issues related to chronic limb ischemia (ie, similar manifestations in patients who present more than two weeks after symptom onset) are discussed separately.

An aneurysm is a bulge in a blood vessel caused by a weakness in the blood vessel wall. As blood passes through the weakened blood vessel, the blood pressure causes it to bulge outwards like a balloon.Exactly what causes the blood vessel wall to weaken is unclear, though hardening of the arteries, smoking and high blood pressure are thought to increase the risk of an aneurysm.